October 12, 2009

Tilted Craters

Most projectiles don't hit flat plains, but instead smash into pre-existing craters and mountains. One of the most extreme variations of elevations for an impact is the rim of a big and deep crater. Clavius, at 5 km deep, has a wide rim that records at least two craters that had the misfortune of hitting it. Porter and Rutherfurd are both relatively young complex craters (both with diameter of 51 km) with one part of their rim near the top of Clavius' rim and the other side nearly on Clavius' floor. Porter - at bottom left on this south up view - has a wide, slump-filled southern wall, whereas the wall near the floor of Clavius is narrow, low and devoid of slumped material. Rutherfurd is similar, with a wide mass of material that slide down from the high southern wall; its floor and central peak also appear to be displaced toward the Clavius side. I am sure that when elevations become available that both of these craters will have tilted rims. A smaller example of a tilted crater is Clavius L, cutting the far right of Clavius' rim. This crater has a wide and high wall to the right and a much lower and narrower wall on the low side. The material that slid down the right wall has piled into a jumble covering the floor. Can you find more tilted craters on other parts of the Moon?